1,3 disubstituted pyrrolidines as α-2-adrenoceptor antagonists

ABSTRACT

The invention provides compounds of formula (I) wherein R 0 , R 1 , R 2  and A are as defined in the description, and the preparation thereof. The compounds of formula (I) have high affinity as α 2  adrenoceptors and hence are useful as pharmaceuticals.

This application is a 371 of International Application PCT/EP 01/00861, filed Jan. 26, 2001.

The present invention relates to novel 1,3-disubstituted pyrrolidines, their preparation, their use as pharmaceuticals and pharmaceutical compositions containing them.

More particularly the invention provides a compound of formula I

wherein

-   -   R₀ is hydrogen or (C₁₋₄)alkyl,     -   R₁ is halogen, hydroxy, (C₁₋₄)alkyl, (C₁₋₄)alkoxy,         (C₂₋₅)alkenyloxy, trifluoromethyl or trifluoromethoxy, and can         also be hydrogen if A is a group of formula (b), (c), (f) or         (g),     -   R₂ is hydrogen or as defined for R₁, or, when in ortho position         to R₁, can also form with R₁ a methylenedioxy group, and     -   A is tetrahydropyran-4-yl or a group of formula         wherein     -   m is 1 to 3,     -   X is O, S or CH═CH,     -   R₃ is hydrogen, halogen, hydroxy, (C₁₋₄)alkyl,         hydroxy(C₁₋₄)alkyl, (C₁₋₄)alkoxy, trifluoromethyl,         (C₁₋₄)alkylsulfonylamino, benzyloxy, carbamoyl,         (C₁₋₄)alkylcarbamoyl or di(C₁₋₄)alkylcarbamoyl,     -   R₄ and R₅ are hydrogen, halogen, (C₁₋₄)alkyl or (C₁₋₄)alkoxy,     -   R₆ is hydrogen, halogen or (C₁₋₄)alkyl,     -   R₇ is hydrogen, (C₁₋₆)alkyl or (C₃₋₇)cycloalkyl(C₁₋₄)alkyl,     -   R₈ is hydrogen, halogen, hydroxy, (C₁₋₄)alkyl, (C₁₋₄)alkoxy,         amino, (C₂₋₅)alkanoylamino, benzoylamino,         (C₁₋₄)alkylsulfonylamino, benzylsulfonylamino,         furylcarbonylamino, carbamoyl, (C₁₋₄)alkylcarbamoyl or         di(C₁₋₄)alkylcarbamoyl, and     -   R₉ is hydrogen, halogen, (C₁₋₄)alkyl or phenyl, or     -   R₈ and R₉ together are —O—(CH₂)_(m)—O— wherein m is as defined         above,     -   R₁₀ is hydrogen, (C₁₋₄)alkyl, (C₃₋₆)cycloalkyl(C₁₋₄)alkyl,         (C₁₋₄)alkylcarbonyl, (C₃₋₆)cycloalkylcarbonyl,         (C₁₋₄)alkoxycarbonyl, benzyl, benzyloxycarbonyl, benzoyl,         (C₁₋₄)alkylsulfonyl, phenylsulfonyl, benzylcarbonyl,         benzylsulfonyl, 2-furylcarbonylamino or         N—(C₁₋₄)alkyl-N-(2-furylcarbonyl)amino, and     -   R₁₁ is hydrogen or (C₁₋₄)alkoxy,         in free base or acid addition salt form.

On account of the asymmetical carbon atom(s) present in the compounds of formula I and their salts, the compounds may exist in optically active form or in form of mixtures of optical isomers, e.g. in form of racemic mixtures. All optical isomers and their mixtures including the racemic mixtures are part of the present invention.

Halogen is fluorine, chlorine, bromine or iodine, preferably fluorine or chlorine.

Any alkyl and alkoxy radicals are branched or straight chain radicals. They are preferably methyl or methoxy groups.

In a further aspect the invention provides a process for the production of the compounds of formula I and their salts, whereby a compound of formula II

wherein R₁ and R₂ are as defined above, is alkylated and the resulting compound is recovered in free base form or as an acid addition salt.

The alkylation can be effected in accordance to conventional procedures, for example using an appropriate compound of formula Y—CHR_(O)-A, wherein R_(O) and A are as defined above and Y is iodine, bromine, chlorine, mesyloxy or tosyloxy, in the presence of a base and in an inert solvent, preferably at elevated temperature, e.g. as described in Example 1. Alternatively a compound R_(o)—CO-A, wherein R_(o) and A are as defined above, can be used (reductive alkylation), e.g. as described in Example 4. For the preparation of a compound of formula I wherein R_(O) is hydrogen, the alkylation can also be effected by acylation with an acid A-COOH, wherein A is as defined above, and subsequent reduction, e.g. as described in Example 2.

For the preparation of a compound of formula I wherein A is a group of formula (c) or (e), the substituent R₇ or R₁₀ may suitably be introduced after the alkylation or acylation/reduction of the compound of formula II, e.g. as described in Example 3.

Compounds of formula I wherein A is as defined above but free from reduceable functional groups (hereinafter A′), can also be obtained by reduction of a compound of formula III

wherein R_(o), R₁, R₂ and A′ are as defined above, obtained by ring closure of a diacid of formula IV

wherein R₁ and R₂ are as defined above, with an amine H₂N—CHR₀-A′, wherein R₀ and A′ are as defined above.

Working up of the reaction mixtures obtained according to the above process and purification of the compounds thus obtained may be carried out in accordance to know procedures.

Compounds of formula I in optically pure form can be obtained from the corresponding racemates according to well-known procedures, or using optically pure starting materials, e.g. as described in Examples 2 to 5.

Acid addition salts may be produced in known manner from the free base forms and vice-versa.

The starting compounds of formulae II, IV, Y—CHR_(o)-A and H₂N—CHR_(o)-A are known or may be obtained from known compounds, using conventional procedures.

The compounds of formula I and their pharmaceutically acceptable acid addition salts, hereinafter referred to as agents of the invention, exhibit valuable pharmacological properties when tested in vitro and in animals, and are therefore useful as pharmaceuticals.

In binding assays, the agents of the invention display high affinity at α₂ adrenoceptor subtypes, with selectivity to α_(2C), as shown in a radioligand binding assay using ³H-RX821002 as a ligand and membranes from CHO K1 cells expressing the recombinant human α₂ adrenoceptor subtypes. In this assay, agents of the invention exhibit pK_(d) values of about 6 to about 10.

In in vitro antagonist experiments using cAMP-based luciferase reporter gene assays based on transfected CHO K1 cells stably expressing the recombinant human α₂ receptors, in presence of the α₂ agonists UK 14,304 or noradrenaline, agents of the invention act as competitive antagonists at the α₂ receptors with pK_(B) values of about 6 to about 9.

In vivo, the agents of the invention inhibit loxapine-induced catalepsy in rats [cf. Kalkman H. O. et al., Br. J. Pharmacol. 124:1550-1556 (1998)] at doses of about 0.3 to about 30 mg/kg s.c.

Furthermore the agents of the invention inhibit amphetamine induced locomotion in rats at doses of about 0.3 to about 30 mg/kg s.c. Locomotion (ambulatory activity) is measured as the number of consecutive infrared interruptions in an appropriate device during a period of 15 min. directly following s.c. injection of amphetamine (1 mg/kg) or solvent (physiological saline) at t=0. The compound or the solvent are administered at t=−30 min.

In view of the above, the agents of the invention are useful as antipsychotics in the treatment of schizophrenia, in the treatment of depression (including bipolar disorders) and more generally in the treatment of any condition associated with a deficiency of noradrenaline in the central or peripheral nervous system which is compensated by α-antagonists via blockade of presynaptic α2 receptors, such as cognition deficits, Parkinson disease, drug abuse, attention deficit hyperactivity disorders, glaucoma, diabetes and erectile dysfunction.

For the above-mentioned indications, the appropriate dosage will of course vary depending upon, for example, the compound employed, the host, the mode of administration and the nature and severity of the condition being treated. However, in general, satisfactory results in animals are indicated to be obtained at a daily dosage of from about 0.1 to about 100, preferably from about 0.5 to about 100 mg/kg animal body weight. In larger mammals, for example humans, an indicated daily dosage is in the range from yout 1 to about 500, preferably from about 1 to about 300 mg of an agent of the invention, conveniently administered, for example, in divided doses up to four times a day or in sustained release form.

The agent of the invention may be administered by any conventional route, in particular enterally, preferably orally, for example in the form of tablets or capsules, or parenterally, for example in the form of injectable solutions or suspensions.

In accordance with the foregoing, the present invention also provides an agent of the invention, for use as a pharmaceutical, e.g. for the treatment of schizophrenia.

The present invention furthermore provides a pharmaceutical composition comprising an agent of the invention in association with at least one pharmaceutical carrier or diluent. Such compositions may be manufactured in conventional manner. Unit dosage forms contain, for example, from about 0.25 to about 150, preferably from 0.25 to about 25 mg of a compound according to the invention.

For all the above indications, the preferred compounds are (R)-1-isopropyl-5-[3-(2-methoxyphenyl)pyrrolidin-1-ylmethyl]-1H-pyridin-2-one and (R)-1-(2,3,-dihydro-benzo-[1,4]dioxin-6-ylmethyl)-3-(2-methoxyphenyl)pyrrolidine. In the above-mentioned loxapine-induced catalepsy test, both compounds show with 0.3-3 mg/kg s.c. a long lasting, dose-dependent inhibition of catalepsy. An oral dose of 10 mg/kg produces similar inhibition as 3 mg/kg s.c. In the above mentioned amphetamine-induced locomotion test, both compounds dose-dependently reduce locomotion at 0.1, 0.3 and 1 mg/kg s.c. (first mentioned compound) and 1, 3 and 10 mg/kg s.c. (second compound).

The preferred indications are schizophrenia and depression.

Moreover the present invention provides the use of an agent of the invention, for the manufacture of a medicament for the treatment of any condition mentioned above.

In still a further aspect the present invention provides a method for the treatment of any condition mentioned above, in a subject in need of such treatment, which comprises administering to such subject a therapeutically effective amount of an agent of the invention.

The following examples illustrate the invention. The temperatures are given in degrees Celsius and are uncorrected.

EXAMPLE 1 1-(1.4-Dioxaspiro[4.5]dec-8-ylmethyl)-3-(2-methoxyphenyl)pyrrolidine

1 g of 3-(2-Methoxyphenyl)pyrrolidine is dissolved in 60 ml of dioxane and 0.85 g Nal, followed by 1.2 ml of N,N-ethyldiisopropylamine and 1.5 g of 8-bromomethyl-1.4-dioxaspiro[4.5]decane, dissolved in 5 ml of dioxane, are added. The reaction mixture is stirred overnight at 80°, evaporated and the residue extracted with ethylacetate/2N Na₂CO₃, followed by aqueous NaCl. The combined, dried and evaporated organic phases yields an oily residue which is purified by flash chromatography on silica gel using t-butylmethylether as a solvent system providing the product as an oil. MS (EI): M⁺=331; NMR (DMSO): 1.1 (2H, m), 1.45 (3H, m), 1.6-1.8 (5H, m), 2.15 (1H, m), 2.25 (2H, m), 2.4 (1H, t), 2.6 (2H, m), 2.8 (1H, t), 3.6 (1H, t), 3.75 (3H, s), 3.85 (4H, s), 6.9 (2H, dd), 7.15 (1H, t), 7.3 (1H, d).

EXAMPLE 2 (+)-5-[3-(2-methoxyphenyl)pyrrolidin-1-ylmethyl]-1H-pyridin-2-one

10.5 g of (−)-5-[3-(2-methoxyphenyl)pyrrolidin-1-carbonyl]-1H-pyridin-2-one dissolved in 100 ml of THF are added at 0° to a suspension of 6.7 g of LiAlH₄ in 200 ml of THF. The temperature of the reaction mixture is allowed to reach room temperature while stirring is continued for 17 hours. Subsequently, the reaction mixture is hydrolysed with NH₄Cl solution and filtered. The filtrate is evaporated and partitioned between CH₂Cl₂ and 1N Na₂CO₃, followed by aqueous NaCl. The combined organic phases are dried and evaporated and the resulting oil purified by flash chromatography on silica gel using CH₂Cl₂/MeOH 9/1 as solvent system providing the product as an oil: [α_(D) ²⁵]=+31.4° (c=1.0, EtOH); MS (EI): M⁺=284; NMR (DMSO): 1.75 (1H, m), 2.15 (1H, m), 2.4 (1H, t), 2.6 (2H, m), 2.8 (1H, t), 3.3-3.4 (2H, m), 3.6 (1H, m), 3.75 (3H, s), 6.3 (1H, d), 6.85-6.95 (2H, m), 7.15 (1H, t), 7.2 (1H, s), 7.25 (1H, d), 7.45 (1H, dd), 11.4 (1H, s).

The starting (−)-5-[3-(2-methoxyphenyl)pyrrolidin-1-carbonyl]-1H-pyridin-2-one is prepared as follows:

6.26 g of 6-hydroxynicotinic acid are suspended in 300 ml of DMF and 9.3 g N,N′-dicyclohexylcarbodiimide, followed by 6.1 g of 1-hydroxybenztriazole are added. After 30 minutes of stirring at room temperature, 8.0 g of (−)-3-(2-methoxyphenyl)pyrrolidine, dissolved in 45 ml of DMF, is added to the resulting solution and stirring continued overnight. Dicyclohexylurea is filtered off, the resulting filtrate evaporated and the residue partitioned between ethylacetate and 2N HCl, followed by aqueous NaCl solution. The combined organic phases are dried and evaporated and the resulting residue purified by flash chromatography on silica gel using CH₂Cl₂/MeOH/conc. aqueous NH₄OH 95/4.5/0.5 as solvent system providing the product as a white foam: [α_(D) ²⁵]=−34.7° (c=1.0, EtOH); MS (Cl): MH⁺=299; NMR (DMSO): 2.05 (1H, m), 2.15 (1H, m), 3.45-3.9 (8H, m), 6.35 (1H, d), 6.9-7.05 (2H, m), 7.25 (2H, m), 7.65 (1H, dd), 7.75 (1H, s), 11.9 (1H, s).

EXAMPLE 3 (+)-1-Isopropyl-5-[3-(2-methoxyphenyl)pyrrolidin-1-ylmethyl]-1H-pyridin-2-one and (+)-2-Isopropoxy-5-[3-(2-methoxyphenyl)pyrrolidin-1-ylmethyl]-1H-pyridine

9.75 g of (+)-5-[3-(2-methoxyphenyl)pyrrolidin-1-ylmethyl]-1H-pyridin-2-one (example 2) are dissolved in 170 ml of toluene. 14.2 g of Na₂CO₃, followed by 6.9 ml of isopropyl-iodide are added to the solution which is stirred at 100° overnight. Subsequently, another 3.4 g of isopropyliodide are added and stirring continued for additional 17 hours. The reaction solution is extracted with water and the combined organic phases dried and evaporated resulting in an oily residue which is purified by flash chromatography on silica gel using CH₂Cl₂/MeOH/conc. aqueous NH₄OH 95/4.5/0.5 as solvent system which provides (+)-1-Isopropyl-5-[3-(2-methoxyphenyl)pyrrolidin-1-ylmethyl]-1H-pyridin-2-one {[α_(D) ²⁵]=+19.7° (c=1.0, EtOH); MS (Cl): MH⁺=327; NMR (DMSO, 120°): 1.3 (6H, d), 1.95 (1H, m), 2.3 (1H, m), 2.7-3.4 (4H, m), 3.6-3.8 (3H, m), 3.8 (3H, s), 5.0 (1H, q), 6.35 (1H, d) 6.9-7.0 (2H, m), 7.2 (1H, t), 7.3 (1H, m), 7.4 (1H, m), 7.6 (1H, m)} and (+)-2-Isopropoxy-5-[3-2-methoxyphenyl)pyrrolidin-1-ylmethyl]-1H-pyridine {[α_(D) ²⁵]=+22.8° (c=1.0, EtOH); MS (EI): M+=326; NMR (DMSO): 1.3 (6H, d), 1.75 (1H, m), 2.15 (1H, m), 2.4 (1H, t), 2.65 (2H, m), 2.8 (1H, t), 3.5-3.65 (3H, m), 3.75 (3H, s), 5.2 (1H, m), 6.7 (1H, d), 6.85-6.95 (2H, m), 7.15 (1H, t), 7.3 (1H, d), 7.6 (1H, m), 8.05 (1H, s)}

EXAMPLE 4 (+)-1-(2,3-Dihydrobenz[1.4]dioxin-6-methyl)-3-(2-methoxyphenyl)pyrrolidine

1.77 g of (−)-3-(2-methoxyphenyl)pyrrolidine, followed by 1.8 g of 2,3-dihydrobenz[1.4]-dioxine-6-carbaldehyde are dissolved in 40 ml of MeOH. 1.26 g of NaCNBH₃ is added and the reaction mixture stirred during 3 hours at room temperature. The solvent is evaporated and the residue partitioned between ethylacetate and water. The organic phases are combined, dried and evaporated and the resulting oily residue purified by flash chromatography on silica gel using ethylacetate/hexane 1/9 as solvent system. The product is obtained as an oil which is transformed into the hydrochloride salt: mp 201-202°; [α_(D) ²⁰]=+9.7° (c=1.0, MeOH); MS (ES): MH⁺=326; NMR (DMSO/NaOD): 1.7 (1H, m), 2.15 (1H, m), 2.35 (1H, q), 2.6-2.7 (2H, m), 2.8 (1H, t), 3.45 (1H, q), 3.55 (1H, q), 3.75 (3H, s), 4.2 (4H, s), 6.75-6.95 (5H, m), 7.15 (1H, t), 7.25 (1H, d).

EXAMPLE 5 (−)-2-[1-(2,3-Dihydrobenzo[1.4]dioxin-6-ylmethyl)pyrrolidin-3-yl]phenol

450 mg of (−)-2-pyrrolidin-3ylphenol, followed by 520 mg of of 2,3-dihydrobenz[1.4]-dioxine-6-carbaldehyde are dissolved in 10 ml of MeOH. The pH is adjusted to 5.5 by addition of acetic acid and the reaction solution is stirred for 2 hours, before 443 mg of NaCNBH₃ is added in portions. Stirring is continued overnight, the solvent subsequently evaporated and the residue purified by flash chromatography on silica gel with CH₂Cl₂/EtOH/conc. aqueous NH₄OH 95/4.5/0.5 which provides the product as an oil: [α_(D) ²⁰]=−35.6° (c=0.75, EtOH); MS (EI): M⁺=311; NMR (DMSO): 1.7 (1H, m), 2.2-2.4 (2H, m), 2.6 (1H, t), 2.75 (1H, dd), 2.95 (1H, t), 3.4 (1H, m), 3.6 (2H, q), 4.25 (4H, s), 6.65 (1H, t), 6.7 (1H, d), 6.75-6.85 (3H, m), 6.95-7.05 (2H, m).

The starting (−)-5-[3-(2-methoxyphenyl)pyrrolidin-1-carbonyl]-1H-pyridin-2-one is prepared as follows:

500 mg of (−)-3-(2-methoxyphenyl)pyrrolidine are dissolved in 12 ml of CH₂Cl₂, 8.5 ml of a 1 M BBr₃ solution in CH₂Cl₂ is addded dropwise at 0° and stirring continued overnight. The reaction mixture is poured on 1N Na₂CO₃ solution, extracted with CH₂Cl₂ and the organic phases washed with brine, dried, evaporated and purified by flash chromatography on silica gel with CH₂Cl₂/EtOH/conc. aqueous NH₄OH 88/10.8/1.2 providing the product as an oil: MS (EI): M⁺=163; NMR (DMSO, 120°): 1.85 (1H, m), 2.2 (1H, m), 2.8 (2H, broad), 2.95-3.05 (2H, m), 2.2-2.4 (2H, m), 3.5 (1H, m), 6.7 (1H, t), 6.8 (1H, d), 7.05 (1H, m), 7.1 (1H, dd).

EXAMPLE 6 1-Benzyl-3-(5-chloro-2-methoxyphenyl)pyrrolidine

730 mg of 1-benzyl-3-(5-chloro-2-methoxyphenyl)pyrroline-2,5-dione are dissolved in 2 ml of acetylchloride and stirred at room temperature for 24 hours. The acetylchloride is evaporated, the residue dried and added to a suspension of 295 mg of LiAlH₄ in 15 ml of ether. The reaction mixture is stirred during 30 minutes, hydrolyzed, filtered and partitioned between CH₂Cl₂ and 2N Na₂CO₃, followed by aqueous NaCl. The combined, dried and evaporated organic phases yield an oil which is purified by flash chromatography using ethylacetate/hexane 1/1 providing the product as a colorless oil: MS (Cl): MH⁺=302; NMR (DMSO): 1.7 (1H, m), 2.2 (1H, m), 2.4-2.8 (5H, m), 3.6 (2H, q), 3.75 (3H, s), 6.95 (1H, d), 7.15-7.35 (7H, m).

The starting 1-Benzyl-3-(5-chloro-2-methoxyphenyl)pyrroline-2,5-dione is prepared as follows:

1.0 g of 2-(5-chloro-2-methoxyphenyl)succinic acid is suspended in 50 ml of xylene, 0.47 ml of benzylamine is added and the mixture refluxed for 8 hours with separation of water. The solvent is evaporated and the residue taken up in ethylacetate and extracted with 2N HCl, followed by 2N NaOH and aqueous NaCl. The organic layer is dried, filtered and the solvent evaporated. The dried residue is purified by flash chromatography using t-butylmethylether/hexane 1/1 providing the amorphous product: MS (EI): M⁺=329; NMR (DMSO): 2.65 (1H, dd), 3.1 (1H, dd), 3.45 (3H, s), 4.2 (1H, dd), 4.6 (2H, s), 7.0 (1H, d), 7.25-7.4 (7H, m).

The following compounds of formula I wherein R₀, R₁, R₂ and A have the significancies indicated in the table are produced analogously to Example 1. The compounds marked “A” under “Remarks” are preferably produced analogously to Example 2, the compounds marked “B” preferably analogously to Example 4 or 5, and the compounds marked “C” preferably analogously to Example 3.

Ex. R₀ R₁ R₂ A [α_(D)] MS Remarks 7 H OMe H a; R₃=p-OH, +/− 284 R₄=H (MH⁺/FAB) 8 ″ ″ ″ a; R₃=R₄=H +/− 268 1 (MH⁺/FAB) 9 ″ ″ ″ a; R₃=o-Cl, R₄=H +/− 301 (M⁺/EI) 10 ″ O-CH-(CH₃)₂ ″ a; R₃=R₄=H +/− 295 (M⁺/EI) 11 ″ O-CH₂-CH=CH₂ ″ ″ +/− 293 (M⁺/EI) 12 ″ OMe ″ a; R₃=m-OMe, +/− 298 R₄=H (MH⁺/FAB) 13 ″ ″ ″ a; R₃=p-C(CH₃)₃; +/− 323 R₄=H (M⁺/EI) 14 ″ ″ ″ d; R₈=R₉=H +/− 273 (M⁺/EI) 15 ″ ″ ″ b; m=1, R₅=H +/− 311 (M⁺/EI) 16 Me ″ ″ a; R₃=R₄=H +/− 281 (M⁺/EI) 17 H ″ ″ a; R₃=3-OMe, +/− 327 A R₄=5-OMe (M⁺/EI) 18 ″ ″ ″ d; R₈=benzyl- +/− 456 sulfonylamino, (M⁺/EI) R₉=H 19 ″ ″ ″ d; R₈=OMe, R₉=H +/− 303 (M⁺/EI) 20 ″ ″ ″ e; R₁₀= +/− 375 -COOC(CH₃)₃ (MH⁺/ES) 21 ″ ″ ″ e; R₁₀=benzoyl +/− 379 (MH⁺/ES) 22 ″ ″ ″ d; R₈=OH, R₉=Me +/− 303 (M⁺/EI) 23 ″ ″ ″ d; R₈=OH, +/− 366 R₉=phenyl (MH⁺/ES) 24 ″ ″ ″ d; R₈=benzoyl- +/− 393 amino, R₉=H (MH⁺/ES) 25 ″ ″ ″ d; R₈=-NHCOMe, +/− 331 R₉=H (MH⁺/ES) 26 ″ ″ ″ a; R₃=p-CH₂OH, +/− 298 A R₄=H (MH⁺/ES) 27 ″ ″ ″ a; R₃=p-F, R₄=H +/− 285 (M⁺/EI) 28 ″ ″ ″ a; R₃=m-NHSO₂- +/− 361 Me, R₄=H (MH⁺/ES) 29 ″ ″ ″ a; R₃=p- +/− 338 CON(CH₃)₂, R₄=H (M⁺/EI) 30 ″ ″ 5-F a; R₃=R₄=H +/− 285 2 (M⁺/EI) 31 ″ ″ 5-Me ″ +/− 281 3 (M⁺/EI) 32 ″ ″ 5-OMe ″ +/− 297 (M⁺/EI) 33 ″ ″ 4-OMe ″ +/− 297 (M⁺/EI) 34 ″ ″ 3-OMe ″ +/− 297 (M⁺/EI) 35 ″ ″ H d; R₈=-NHCO-2- +/− 382 furyl, R₉=H (M⁺/EI) 36 ″ ″ ″ f; R₁₁=H +/− 268 A (M⁺/EI) 37 ″ ″ ″ c; R₆=H, R₇=Me +/− 298 A (M⁺/EI) 38 ″ ″ ″ d; R₈=R₉=F +10.3° 309 (c=1/EtOH) (M⁺/EI) 39 ″ ″ 6-OMe a; R₃=R₄=H +/− 297 (M⁺/EI) 40 ″ ″ H c; R₆=H, +19.3° 339 A R₇=cyclo- (c=1/EtOH) (MH⁺/ES) propylmethyl 41 ″ ″ 3-Me a; R₃=R₄=H +/− 282 (MH⁺/ES) 42 ″ ″ H a; R₃=3-OMe, +25.0° 328 R₄=4-OMe (c=0.5/EtOH) (MH⁺ /CI) 43 ″ ″ ″ c; R₆=H, −18.4° 327 A R₇=propyl (c=0.9/EtOH) (MH⁺/ES) 44 ″ ″ ″ a; R₃= +19.3° 338 m-CON(CH₃)₂; (c=1/EtOH) (M⁺ /EI) R₄=H 45 ″ -O-CH₂-O- a; R₃=R₄=H +/− 281 (M⁺/EI) 46 ″ OMe H tetrahydropyran- +11.4° 275 A 4-yl (c=1/EtOH) (M⁺/EI) 47 ″ ″ ″ g; X=O, +/− 309 B X-containing ring (M⁺/EI) in 2, 3 48 ″ ″ ″ g; X=O, +20.2° 326 X-containing ring (c=0.4/EtOH) (MH⁺/CI) in 3, 4 49 ″ ″ ″ b; m=3, R₅=H +24.5° 340 (c=1/EtOH) ° 50 ″ ″ ″ g; X=CH=CH, +11.7° 320 X-containing ring (c=0.5/EtOH) (MH⁺/ES) in 3, 4 51 ″ H ″ b; m=2, R₅=H +/− 296 B (MH⁺/ES) 52 ″ Me ″ ″ +/− 309 B (M⁺/EI) 53 ″ H 4-OMe c; R₆=H, +/− 326 C R₇=isopropyl (M⁺/EI) 54 ″ ″ 4-Cl ″ +/− 331 C (MH⁺/ES) 55 ″ OMe 5-F ″ +14.5° 345 C (c=1/EtOH) (MH⁺/ES) 56 ″ ″ 6-OMe b; m=2, R₅=H +/− 356 B (MH⁺/ES) 57 ″ OCF₃ H ″ +/− 380 B (MH⁺/ES) 58 ″ CF₃ H ″ +/− 364 B (MH⁺/ES) 59 ″ H 4-CF₃ ″ +/− 363 B (M⁺/EI) 60 ″ OMe 3-Me c; R₆=H, +/− 341 C R₇=isopropyl (MH⁺/ES) 61 ″ ″ 5-Me b; m=2, R₅=H +/− 340 4, B (MH⁺/ES) 62 ″ H 4-F c; R₆=H, +32.0° 315 C R₇=isopropyl (c=1/EtOH) (MH⁺/ES) 63 ″ F H ″ +/− 315 C (MH⁺/EI) Mp = methyl 1: Mp = 138° (hydrogenfumarate) 2: Mp = 142-440° (hydrogenfumarate) 3: Mp = 146-149° (hydrogenfumarate) 4: Mp = 164-149° (hydrochloride) 

1. A compound of formula I

wherein R₀ is hydrogen or (C₁₋₄)alkyl; R₁ is halogen, hydroxy, (C₁₋₄)alkyl, (C₁₋₄)alkoxy, (C₂₋₅)alkenyloxy, trifluoromethyl or trifluoromethoxy, and can also be hydrogen if A is a group of formula (c), (f) or (g); R₂ is hydrogen or as defined for R₁ or, when in ortho position to R₁, can also form with R₁ a methylenedioxy group; and A is a group of formula

wherein X is O, S or CH═CH; R₆ is hydrogen, halogen or (C₁₋₄)alkyl; R₇ is hydrogen, (C₁₋₄)alkyl or (C₃₋₇)cycloalkyl(C₁₋₄)alkyl; R₁₀ is hydrogen, (C₁₄)alkyl, (C₃₋₆)cycloalkyl(C₁₋₄)alkyl, (C₁₋₄)alkylcarbonyl, (C₃₋₆)cycloalkylcarbonyl, (C₁₋₄)alkoxycarbonyl, benzyl, benzyloxycarbonyl, benzoyl, (C₁₋₄)alkylsulfonyl, phenylsulfonyl, benzylcarbonyl, benzylsulfonyl, 2-furylcarbonylamino or N—(C₁₋₄)alkyl-N-(2-furylcarbonyl)amino; and R₁₁ is hydrogen or (C₁₋₄)alkoxy, in free base or acid addition salt form.
 2. A process for the production of a compound of formula I as defined in claim 1, which comprises alkylating a compound of formula II

wherein R₁ and R₂ are as defined in claim 1, and recovering the resulting compound in free base form or as an acid addition salt.
 3. A compound of formula I as defined in claim 1, wherein A is a group of formula (c), in free base or acid additional salt form.
 4. (S)-1-isopropyl-5-[3-(2-methoxyphenyl)pyrrolidin-1-ylmethyl]-1H-pyridin-2-one in free base or acid addition salt form.
 5. A pharmaceutical composition comprising a pharmaceutically acceptable carrier or diluent and a therapeutically effective amount of a compound according to claim 1, in free base or pharmaceutically acceptable salt form.
 6. A method of treating a disease or condition which is responsive to an α2 adrenoceptor antagonist in a subject in need of such treatment, selected from the group consisting of schizophrenia, depression, Parkinson's disease, cognition deficits, drug abuse, attention deficit hyperactivity disorders, glaucoma, diabetes, and erectile dysfunction, which comprises administering to such subject a therapeutically effective amount of a compound of claim 1, in free base or pharmaceutically acceptable acid addition salt form.
 7. 5-[(R)-3-(4-Fluorophenyl)pyrrolidin-1-ylmethyl]-1-isopropyl-1H-pyridin-2-one, in free base or acid addition salt form. 